U.S. patent application number 13/368255 was filed with the patent office on 2012-05-31 for process chamber component having yttrium-aluminum coating.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Nianci HAN, Hong Shih, Li Xu.
Application Number | 20120135155 13/368255 |
Document ID | / |
Family ID | 38970413 |
Filed Date | 2012-05-31 |
United States Patent
Application |
20120135155 |
Kind Code |
A1 |
HAN; Nianci ; et
al. |
May 31, 2012 |
PROCESS CHAMBER COMPONENT HAVING YTTRIUM-ALUMINUM COATING
Abstract
A substrate processing chamber component comprising a chamber
component structure having an yttrium-aluminum coating. The
yttrium-aluminum coating comprises a compositional gradient through
a thickness of the coating.
Inventors: |
HAN; Nianci; (San Jose,
CA) ; Xu; Li; (San Jose, CA) ; Shih; Hong;
(Walnut, CA) |
Assignee: |
Applied Materials, Inc.
|
Family ID: |
38970413 |
Appl. No.: |
13/368255 |
Filed: |
February 7, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11982039 |
Oct 31, 2007 |
8110086 |
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13368255 |
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10824123 |
Apr 13, 2004 |
7371467 |
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11982039 |
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10042666 |
Jan 8, 2002 |
6942929 |
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10824123 |
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Current U.S.
Class: |
427/453 ;
118/504 |
Current CPC
Class: |
Y10T 428/12778 20150115;
C23C 30/00 20130101; Y10T 428/12736 20150115; C23C 28/345 20130101;
C23C 28/42 20130101; H01L 21/67115 20130101; C23C 28/34 20130101;
H01J 37/32477 20130101; C23C 28/3455 20130101; C25D 3/54 20130101;
Y10T 428/12458 20150115; Y10T 428/12806 20150115; C23C 30/005
20130101; C23C 28/321 20130101; C25D 5/50 20130101; C25D 3/56
20130101; C25D 3/44 20130101; C25D 5/18 20130101; Y10T 428/12618
20150115; C23C 28/322 20130101; Y10T 428/12611 20150115; C23C
16/4404 20130101; C23C 16/4411 20130101; Y10T 428/12667 20150115;
C23C 28/36 20130101 |
Class at
Publication: |
427/453 ;
118/504 |
International
Class: |
C23C 4/10 20060101
C23C004/10; B05C 11/00 20060101 B05C011/00 |
Claims
1. A substrate processing chamber component comprising: (a) a
chamber component structure; and (b) an yttrium-aluminum coating on
the chamber component structure, the yttrium-aluminum coating
having a compositional gradient through a thickness of the
coating.
2. A component according to claim 1 wherein the chamber component
structure and the yttrium-aluminum coating form a unitary and
continuous structure.
3. A component according to claim 1 wherein the yttrium-aluminum
coating comprises a thickness of from about 0.5 mil to about 8
mils.
4. A component according to claim 1 wherein the yttrium-aluminum
coating comprises yttrium-aluminum oxide.
5. A component according to claim 1 wherein the yttrium-aluminum
coating comprises YAG.
6. A component according to claim 1 wherein the yttrium-aluminum
coating comprises a plasma sprayed coating.
7. A component according to claim 1 wherein the chamber component
structure comprises a metal alloy composed of yttrium and
aluminum.
8. A component according to claim 1 wherein the chamber component
structure comprises an yttrium content of less than about 50% by
weight.
9. A component according to claim 1 wherein the chamber component
structure comprises a process chamber wall, a portion of an
enclosure wall or wall liner, substrate support, substrate
transport, gas supply, gas energizer or gas exhaust.
10. A substrate processing chamber component comprising: (a) a
chamber component structure; and (b) a coating on the chamber
component structure, the coating comprising a metal alloy of
yttrium and aluminum.
11. A component according to claim 10 wherein the coating comprises
a compositional gradient through a thickness of the coating.
12. A component according to claim 10 wherein the chamber component
structure and the coating form a unitary and continuous
structure.
13. A component according to claim 10 wherein the coating comprises
yttrium-aluminum oxide.
14. A component according to claim 10 wherein the coating comprises
YAG.
15. A component according to claim 10 wherein the coating comprises
a plasma sprayed coating.
16. A method of manufacturing a substrate processing chamber
component, the method comprising: (a) forming a chamber component
structure; and (b) plasma spraying a yttrium-aluminum coating on
the chamber component structure, the yttrium-aluminum coating
having a compositional gradient through a thickness of the
coating.
17. A method according to claim 16 comprising plasma spraying the
yttrium-aluminum coating to form yttrium-aluminum oxide.
18. A method according to claim 16 comprising plasma spraying the
yttrium-aluminum coating such that the coating is absent a discrete
or sharp crystalline boundary with the chamber component
structure.
19. A method according to claim 16 comprising forming a chamber
component structure comprising a metal alloy composed of yttrium
and aluminum.
20. A component according to claim 1 comprising forming a chamber
component structure comprising a process chamber wall, a portion of
an enclosure wall or wall liner, substrate support, substrate
transport, gas supply, gas energizer or gas exhaust.
Description
CROSS-REFERENCE
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/982,039, filed Oct. 31, 2007, entitled
"Method of Manufacturing a Process Chamber Component Having
Yttrium-Aluminum Coating", which is a divisional of U.S. Pat. No.
7,371,467, application Ser. No. 10/824,123, entitled "Process
Chamber Component Having Electroplated Yttrium Containing Coating"
filed on Apr. 13, 2004, which is a continuation-in-part of U.S.
Pat. No. 6,942,929, application Ser. No. 10/042,666, entitled
"Process Chamber Having Yttrium-Aluminum Coating," filed on Jan. 8,
2002, all of which are assigned to Applied Materials, Inc. and are
herein incorporated by reference and in their entireties.
BACKGROUND
[0002] In the processing of substrates, for example, substrate
etching processes, substrate deposition processes, and substrate
and chamber cleaning processes, gases such as halogen or oxygen
gases are used. The gases, especially when they are energized, for
example by RF power or microwave energy, can corrode or erode
(which terms are used interchangeably herein) components of the
chamber, such as the chamber wall. For example, chamber components
made of aluminum can be corroded by halogen gases to form
AlCl.sub.3 or AlF.sub.3. The corroded components need to be
replaced or cleaned off resulting in chamber downtime which is
undesirable. Also, when the corroded portions of the components
flake off and contaminate the substrate they reduce substrate
yields. Thus, it is desirable to reducing corrosion of the chamber
components.
[0003] The corrosion or erosion resistance of the aluminum chamber
components may also be improved by forming an anodized aluminum
oxide coating on the components. For example, an aluminum chamber
wall may be anodized in an electroplating bath to form a protective
coating of anodized aluminum oxide. The anodized coating increases
the corrosion resistance of the aluminum chamber, but it still is
sometimes degraded by highly energized or erosive gas compositions,
for example, by an energized gas comprising a plasma of a fluorine
containing gas, such as CF.sub.4, to form gaseous byproducts such
as AlF.sub.3.
[0004] Conventional chamber components formed out of bulk ceramic
materials or plasma sprayed ceramic coatings exhibit better erosion
resistance but are susceptible to other failure modes. For example,
chamber components formed out of a bulk material comprising a
mixture of yttrium oxide and aluminum oxide, are brittle and tend
to fracture when machined into a shape of a component. Bulk ceramic
material may also be susceptible to cracking during operation of
the chamber. Chamber components have also been made with plasma
sprayed coatings. However, the thermal expansion mismatch between
the coating and the underlying component material can cause thermal
strains during heating or cooling that result in cracking or
flaking off of the ceramic coating from the underlying component.
Thus, conventional ceramic components do not always provide the
desired corrosion and failure resistance.
[0005] For these and other reasons, further development of ceramic
coatings and materials that provide improved corrosion or erosion
resistance to corrosive energized gases is needed.
SUMMARY
[0006] A substrate processing chamber component comprising a
chamber component structure having an yttrium-aluminum coating. The
yttrium-aluminum coating comprises a compositional gradient through
a thickness of the coating.
[0007] A substrate processing chamber component comprising a
chamber component structure and a coating on the chamber component
structure, the coating comprising a metal alloy of yttrium and
aluminum.
[0008] A method of manufacturing a substrate processing chamber
component, the method comprising forming a chamber component
structure, and plasma spraying a yttrium-aluminum coating on the
chamber component structure, the yttrium-aluminum coating having a
compositional gradient through a thickness of the coating.
DRAWINGS
[0009] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying drawings
which illustrate examples of the invention, where:
[0010] FIG. 1a is a schematic sectional side view of a version of
an embodiment of a process chamber according to the present
invention;
[0011] FIG. 1b is a sectional side view of another version of a gas
energizer;
[0012] FIG. 1c is a schematic sectional side view of another
version of the process chamber;
[0013] FIG. 2 is a partial sectional schematic side view of a
chamber component comprising an integral surface coating of
yttrium-aluminum compound;
[0014] FIG. 3a is a flow chart of an embodiment of a process for
anodizing a surface of a metal alloy component to form an integral
surface coating;
[0015] FIG. 3b is a flow chart of an embodiment of a process for
ion implanting a surface of a component to form an integral surface
coating;
[0016] FIG. 4 is a schematic top view of an ion implanter;
[0017] FIG. 5 is a schematic sectional side view of an ion source
in the ion implanter of FIG. 4; and
[0018] FIG. 6 is a schematic sectional side view of an
annealer.
DESCRIPTION
[0019] An exemplary apparatus 102 suitable for processing a
substrate 104 comprises a process chamber 106 capable of enclosing
a substrate 104, as shown in FIGS. 1a and 1c. The particular
embodiment of the apparatus 102 shown herein is suitable for
processing substrates 104 such as semiconductor wafers, and may be
adapted by those of ordinary skill to process other substrates 104,
such as flat panel displays, polymer panels, or other electrical
circuit receiving structures. The apparatus 102 is particularly
useful for processing layers, such as etch resistant,
silicon-containing, metal-containing, dielectric, and/or conductor
layers on the substrate 104. The apparatus 102 may be attached to a
mainframe unit (not shown) that contains and provides electrical,
plumbing, and other support functions for the apparatus 102 and may
be part of a multichamber system (not shown). The multichamber
system has the capability to transfer a substrate 104 between its
chambers without breaking the vacuum and without exposing the
substrate 104 to moisture or other contaminants outside the
multichamber system. An advantage of the multichamber system is
that different chambers in the multichamber system may be used for
different purposes. For example, one chamber may be used for
etching a substrate 104, another for the deposition of a metal
film, another for rapid thermal processing, and yet another for
depositing an anti-reflective layer. The process may proceed
uninterrupted within the multichamber system, thereby preventing
contamination of substrates 104 that may otherwise occur when
transferring substrates 104 between various separate individual
chambers for different parts of a process.
[0020] Generally, the process chamber 106 comprises a wall 107,
such as an enclosure wall 103, which may comprise a ceiling 118,
sidewalls 114, and a bottom wall 116 which enclose a process zone
108. The wall 107 may also comprise a chamber wall liner 105, which
lines at least a portion of the enclosure wall 103 about the
process zone 108. In operation, process gas is introduced into the
chamber 106 through a gas supply 130 that includes a process gas
source 138, and a gas distributor 137. The gas distributor 137 may
comprise one or more conduits 136 having one or more gas flow
valves 134, and one or more gas outlets 142 around a periphery of a
substrate support 110 having a substrate receiving surface 180.
Alternatively, the gas distributor 130 may comprise a showerhead
gas distributor (not shown). Spent process gas and etchant
byproducts are exhausted from the chamber 106 through an exhaust
144 which may include a pumping channel that receives spent process
gas from the process zone, a throttle valve 135 to control the
pressure of process gas in the chamber 106, and one or more exhaust
pumps 152.
[0021] The process gas may be energized by a gas energizer 154 that
couples energy to the process gas in the process zone 108 of the
chamber 106. In the version shown in FIG. 1a, the gas energizer 154
comprises process electrodes 139, 141 that are powered by a power
supply 159 to energize the process gas. The process electrodes 139,
141 may include an electrode 141 that is or is in a wall, such as a
sidewall 114 or ceiling 118 of the chamber 106 that may be
capacitively coupled to another electrode 139, such as an electrode
in the support 110 below the substrate 104. Alternatively or
additionally, as shown in FIG. 1b, the gas energizer 154 may
comprise an antenna 175 comprising one or more inductor coils 178
which may have a circular symmetry about the center of the chamber
106. In yet another version, the gas energizer 154 may comprise a
microwave source and waveguide to activate the process gas by
microwave energy in a remote zone 157 upstream from the chamber
106, as shown in FIG. 1c. To process a substrate 104, the process
chamber 106 is evacuated and maintained at a predetermined
sub-atmospheric pressure. The substrate 104 is then provided on the
support 110 by a substrate transport 101, such as for example a
robot arm and a lift pin system. The gas energizer 154 then
energizes a gas to provide an energized gas in the process zone 108
to process the substrate 104 by coupling RF or microwave energy to
the gas.
[0022] At least one component 114 of the chamber 106 comprises an
integral surface coating 117 comprising an yttrium-aluminum
compound, as schematically illustrated in FIG. 2. The underlying
structure 111 of the component 114 and the integral surface coating
117 form a unitary and continuous structure that is absent a
discrete and sharp crystalline boundary therebetween. The integral
surface coating is formed in-situ from the surface of the component
114 using at least a portion of the underlying component material.
By "growing" the surface coating 117 out of the structure of which
the component 114 is fabricated, the surface coating 117 is much
more strongly bonded to the underlying component material structure
than conventional coatings such as plasma sprayed coatings which
have a discrete and sharp boundary between the coating and the
underlying structure. The integral surface coating 117 is formed
from the structure 111 by, for example, anodizing a component
surface 112 comprising a desirable metallic composition or by ion
implantation into the surface 112 of the component 114. The
integral surface coating 117 may also have a compositional gradient
that continuously or gradually varies in composition from an
underlying material composition to a surface composition. As a
result, the integral surface coating 117 is strongly bonded to the
underlying material and this reduces flaking-off of the coating 117
and also allows the coating to better withstand thermal stresses
without cracking.
[0023] The component 114 having the integral surface coating 117
may be the chamber wall 107, such as for example, a portion of an
enclosure wall 103 or liner 105, the substrate support 110, the gas
supply 130, the gas energizer 154, the gas exhaust 144, or the
substrate transport 101. Portions of the chamber component 114 that
are susceptible to corrosion or erosion, such as surfaces 115 of
components 114 that are exposed to high temperatures, corrosive
gases, and/or erosive sputtering species in the process zone 108,
may also be processed to form the integral surface coating 117. For
example, the component 114 may form a portion of the chamber wall
107, such as the chamber wall surface 115, which is exposed to the
plasma in the chamber 106.
[0024] In one version, the integral surface coating 117 comprises
an yttrium-aluminum compound which may be an alloy of yttrium and
aluminum, or one or more compounds having a predefined
stoichiometry, such as a plurality of oxides of yttrium and
aluminum. For example, the yttrium-aluminum compound may be a
mixture of Y.sub.2O.sub.3 and Al.sub.2O.sub.3, such as for example,
yttrium aluminum garnet (YAG). When the integral surface coating
117 is an yttrium aluminum oxide, the coating 117 may have a
concentration gradient of the oxide compounds through the thickness
of the component 114, with a higher concentration of the oxide
compounds typically being present closer to the surface 112 of the
component 114 and the concentration of the oxide compounds
decreasing with increasing distance into the interior structure 111
of the component and away from the surface 112.
[0025] For example, when the integral surface coating 117 comprises
an yttrium aluminum oxide, the regions near the surface 112 tend to
have a higher concentration of oxidized yttrium and aluminum
species while regions towards the component interior 111 have a
lower concentration of the oxidized species. The integral surface
coating 117 of yttrium aluminum oxide exhibits good corrosion
resistance from energized halogenated gases as well as good erosion
resistance from energetic sputtering gases. In particular, the
integral surface coating 117 exhibits good resistance to energized
chlorine containing gases. The composition and thickness of the
integral surface coating 117 is selected to enhance its resistance
to corrosion and erosion, or other detrimental effects. For
example, a thicker integral surface coating 117 may provide a more
substantial barrier to corrosion or erosion of the chamber
component 114, while a thinner coating is more suitable for thermal
shock resistance. The integral surface coating 117 may even be
formed such that the oxidized species, and thus the thickness of
the coating 117, extends throughout the depth of the component or
just on its surface. A suitable thickness of the integral surface
coating 117 may be, for example, from about 0.5 mils to about 8
mils, or even from about 1 mil to about 4 mils.
[0026] In one version, the component 114 comprises a metal alloy
comprising yttrium and aluminum and the integral surface coating
117 is formed by anodizing the surface of the metal alloy. The
metal alloy having the anodized integral surface coating 117 may
form a portion or all of the chamber component 114. The metal alloy
comprises a composition of elemental yttrium and aluminum that is
selected to provide desirable corrosion resistance or other alloy
characteristics. For example, the composition may be selected to
provide a metal alloy having good melting temperature or
malleability to facilitate fabrication and shaping of the chamber
components 114. The composition may also be selected to provide
characteristics that are beneficial during the processing of
substrates, such as resistance to corrosion in an energized process
gas, resistance to high temperatures, or the ability to withstand
thermal shock. In one version, a suitable composition comprises a
metal alloy consisting essentially of yttrium and aluminum.
[0027] The composition of the metal alloy to be anodized is
selected to provide the desired corrosion or erosion resistance
properties for the overlying coating. The composition may be
selected to provide a metal alloy capable of being anodized to form
an anodized integral surface coating 117 that is resistant to
corrosion by an energized gas. For example, the metal alloy
composition may be selected to provide a desired coating
composition of oxidized aluminum and yttrium on the surface 113 of
the metal alloy when anodized in an acidic solution. A suitable
composition of the metal alloy which provides a corrosion resistant
anodized integral surface coating 117 is, for example, a metal
alloy in which yttrium comprises at least about 5% by weight of the
metal alloy, and preferably less than about 80% by weight of the
metal alloy, for example, about 67% by weight of the metal
alloy.
[0028] The metal alloy allows for an integrated or continuous
structure with the overlying integral coating 117 that is
advantageous. The integrated structure provides reduced thermal
expansion mismatch problems between the anodized surface coating
117 and the underlying metal alloy. Instead, the anodized metal
alloy comprising the anodized integral surface coating 117 remains
a substantially unitary structure during heating and cooling of the
metal alloy. Thus, the anodized integral surface coating 117
exhibits minimal cracking or flaking during substrate processing,
and forms a durable corrosion resistant structure with the rest of
the metal alloy.
[0029] In an exemplary method of fabricating the component 114
comprising the metal alloy comprising yttrium and aluminum and
having the anodized integral surface coating 117, a mixture of
yttrium and aluminum is heat softened or melted to form a metal
alloy that is shaped to form a chamber component 113. The surface
113 of the chamber component 114 is cleaned and subsequently
anodized by placing the chamber component 114 in an oxidizing
solution and electrically biasing the chamber component 114.
[0030] FIG. 3a shows a flow chart illustrating an embodiment of an
anodization method of manufacture. The metal alloy comprising
yttrium and aluminum is formed in a desired composition. For
example, a suitable composition may comprise a metal alloy in which
the molar ratio of yttrium to aluminum is about 5:3. The metal
alloy may be formed by, for example, heating a mixture comprising
the desired amounts of yttrium and aluminum to a melting or
softening temperature of the composition to melt the metals and
combine them into a single alloy. While in one version, the metal
alloy may consist essentially of yttrium and aluminum, other alloy
agents, such as other metals, may be melted with the metallic
yttrium and aluminum to aid in the formation of the metal alloy or
to enhance the properties of the metal alloy. For example, cerium
or other rare earth elements may be added.
[0031] The metal alloy is shaped to form the desired chamber
component 114 or portion of the chamber component 114. For example,
a desired shape of the metal alloy may be obtained by casting or
machining the metal alloy. The metal alloy is cast by cooling
molten or otherwise liquefied forms of the metal alloy in a casting
container having a desired shape or form. The casting container may
comprise the same container in which the metallic yttrium and
aluminum are melted to form the alloy 112 or may be a separate
casting container. Cooling of the heated metal alloy results in
solidification of the metal alloy into a shape which conforms to
the shape of the casting container, thus providing the desired
metal alloy shape.
[0032] Once the metal alloy having the desired shape is formed, an
anodization process may be performed to anodize a surface of the
metal alloy, thereby forming the anodized integral surface coating
117 of oxidized species. The metal alloy may also be cleaned before
anodization to remove any contaminants or particulates on the
surface 113 of the metal alloy that might interfere with the growth
of the anodized surface coating. For example, the surface 113 may
be cleaned by immersing the metal alloy in an acidic solution to
etch away contaminant particles or the metal alloy may be
ultrasonically cleaned.
[0033] In one version, the metal alloy is anodized by
electrolytically reacting the surface 113 of the metal alloy with
an oxidizing agent. For example, the metal alloy may be placed in
an oxidizing solution, such as an oxidizing acid solution, and
electrically biased to induce formation of the anodized surface
coating. Suitable acid solutions may comprise, for example, one or
more of chromic acid, oxalic acid and sulfuric acid. The
anodization process parameters, such as the acid solution
composition, electrical bias power, and duration of the process may
be selected to form an anodized integral surface coating 117 having
the desired properties, such as for example a desired thickness or
corrosion resistance. For example, a metal alloy comprising an
anodized surface coating may be formed by anodizing the metal alloy
in an acid solution comprising from about 0.5 M to about 1.5 M of
sulfuric acid with a suitable applied bias power to the electrodes
in the bath for a duration of from about 30 minutes to about 90
minutes, and even about 120 minutes.
[0034] The metal alloy may also be at least partially anodized by
exposing the metal alloy to an oxygen containing gas, such as air.
Oxygen from the air oxidizes the surface 113, thereby forming the
anodized integral surface coating 117. The rate of the anodization
process may be increased by heating the metal alloy and oxygen
containing gas, and by using pure oxygen gas.
[0035] The steps of forming the chamber component 114 comprising
the metal alloy 114 having the anodized integral surface coating
117 may be performed in the order which is most suitable for
fabrication of the chamber component 114, as is known to those of
ordinary skill in the art. For example, the anodization process may
be performed after the metal alloy has been formed into a desired
shape, as described above. As another example, the anodization
process may be performed before the metal alloy 122 is formed into
the desired shape. For example, the metal alloy may be shaped by
welding before or after the anodization process.
[0036] The chamber components 114, such as the chamber wall 107,
gas supply, gas energizer, gas exhaust, substrate transport, or
support, which are at least partially formed from the metal alloy
comprising yttrium and aluminum and having the anodized integral
surface coating 117, provide improved resistance to corrosion of
the component 114 by an energized process gas and at high
processing temperatures. The integrated structure of the metal
alloy having the anodized integral surface coating 117 further
enhances corrosion resistance, and reduces cracking or flaking of
the anodized surface coating. Thus, desirably the chamber
components 114 comprise the metal alloy having the anodized
integral surface coating 117 at regions of the components 114 that
are susceptible to corrosion, such as surfaces 115 of the chamber
wall 107 that are exposed to the process zone, to reduce the
corrosion and erosion of these regions.
[0037] In another aspect of the present invention, an ion implanter
300, as illustrated in FIG. 4, forms the integral surface coating
117 by ion implanting a constituent material of the integral
surface coating 117 into the surface 112 of the component 114. In
this method, the ion implanter 300 fabricates the component 114,
for example, from one or more metals, and implants other metal or
non-metal species into the component 114 by bombarding its surface
112 with energetic ion implantation species. In one embodiment,
energetic yttrium ions are implanted into the surface 112 of a
component 114 comprising aluminum, while in another embodiment
energetic oxygen ions are implanted into the surface 112 of an
yttrium-aluminum alloy. The ion implanter 300 comprises a vacuum
housing 310 to enclose a vacuum environment, and one or more vacuum
pumps 320 to evacuate the vacuum housing 310 to create the vacuum
environment therein. The ion implantation process may be carried
out at room temperature or at higher temperatures. A listing of the
typical process steps is provided in FIG. 3b.
[0038] An ion implanter 300 provides good control of the uniformity
and surface distribution of the material implanted into the surface
112 of the metal alloy. For example, the ion implanter 300 can
control the implantation density with which the implantable ions
are implanted in the component 114 and a penetration depth of the
implanting material in the component 114. The ion implanter 300 can
also provide uniform surface coverage and concentration levels.
Additionally, the ion implanter 300 can also form the integral
surface coating 117 on only certain selected regions of the
component 114, and the distribution of the implanting material at
the edges of the regions may be controlled. In typical ion
implantation methods, a good range of ion doses may be implanted,
such as for example, from about 10.sup.11 to about 10.sup.17
ions/cm.sup.2. In one embodiment, the ion implanter 300 can control
the dose to within .+-.1% within this dose range.
[0039] Typically, the ion implanter 300 comprises an ion source 330
in the vacuum housing 310 to provide and ionize the material to be
implanted to form the integral surface coating 117. In one version,
the ion source 330 contains the implanting material in a solid form
and a vaporization chamber (not shown) is used to vaporize the
solid implanting material. In another version, the ion source 330
provides the implanting material in a gaseous form. For example,
gaseous implanting material may be fed into the ion source 330 from
a remote location, thereby allowing the material to be replenished
in the ion source 330 without opening the vacuum housing 310 or
otherwise disrupting the vacuum environment. The implanting
material may comprise, for example, elemental yttrium or oxygen
which is to be implanted in an aluminum component to form a
component comprising an yttrium-aluminum oxide compound, such as
YAG. Any source of the ionizable material may be used, such as for
example, a gas comprising yttrium, solid yttrium, or oxygen
gas.
[0040] In one embodiment, illustrated in FIG. 5, the ion source 330
comprises a gas inlet 410 through which the gaseous implanting
material is introduced into an ionization zone of an ionization
system 420 to ionize the gaseous implanting material prior to its
delivery to the component surface 112. The gaseous or vaporized
implanting material is ionized by passing the gas or vapor through
a hot cathode electronic discharge, a cold cathode electronic
discharge, or an R.F. discharge. In one version, the ionization
system 420 comprises a heated filament 425. The ion source 330
further comprises an anode 430 and an extraction electrode 440 that
is about an extraction outlet 445, which are incrementally
electrically biased to extract the positive ions from the ionized
gas and form an ion beam 340. In one embodiment, the anode 430 is
biased at from about 70 V to about 130 V, such as at about 100 V.
The extraction electrode 440 may be biased at from about 10 keV to
about 25 keV, such as from about 15 keV to about 20 keV. The
extraction outlet 445 may be shaped to define the shape of the ion
beam 340. For example, the extraction outlet 445 may be a circular
hole or a rectangular slit. A solenoid 450 is provided to generate
a magnetic field that forces the electrons to move in a spiral
trajectory, to increase the ionizing efficiency of the ion source
330. An exemplary suitable range of current of the ion beam 340 is
from about 0.1 mA to about 100 mA, such as from about 1 mA to about
20 mA.
[0041] Returning to FIG. 4, the ion implanter 300 also typically
comprises a series of accelerator electrodes 350 to accelerate the
ion beam 340. The accelerator electrodes 350 are generally
maintained at incrementally increasing levels of electric potential
along the propagation direction of the ion beam 340 to gradually
accelerate the ion beam 340. In one version, the accelerator
electrodes 350 accelerate the ion beam 340 to energies of from
about 50 to about 500 keV, and more typically from about 100 to
about 400 keV. The higher energy ion beams may be used to implant
ions that are relatively heavy or are desirably implanted deep into
the surface 112 of the component 114.
[0042] The ion implanter 300 comprises a beam focuser 360 to focus
the ion beam 340. In one version, the beam focuser 360 comprises a
magnetic field lens (not shown) that generates a magnetic field to
converge the ion beam 340. For example, the magnetic field may be
approximately parallel to the propagation direction of the ion beam
340. The beam focuser 360 may additionally serve to further
accelerate the ion beam 340, such as by being maintained at an
electric potential. In another version, the beam focuser 360
comprises an electrostatic field lens (not shown) that generates an
electric field to converge the ion beam 340. For example, a portion
of the electric field may be approximately orthogonal to the
propagation direction of the ion beam 340.
[0043] In one version, the ion implanter 300 further comprises a
mass analyzer 370 to analyze or select the mass of the ions. In one
version, the mass analyzer 370 comprises a curved channel (not
shown) through which the ion beam 340 may pass. The mass analyzer
370 generates a magnetic field inside the channel to accelerate
ions having a selected ratio of mass to charge along the inside of
the curved channel. Ions that have substantially different ratios
of mass to charge from the selected ions collide with the sides of
the curved channel and thus do not continue to pass through the
curved channel. In one embodiment, by selecting a particular
magnetic field strength, the mass analyzer 370 selects a particular
ratio of mass to charge to allow. In another embodiment, the mass
analyzer 370 determines the mass to charge ratio distribution of
the ion beam 340 by testing a range of magnetic field strengths and
detecting the number of ions passing through the curved channel at
each magnetic field strength. The mass analyzer 370 typically
comprises a plurality of magnet pole pieces made of a ferromagnetic
material. One or more solenoids may be provided to generate
magnetic fields in the vicinity of the magnet pole pieces.
[0044] The ion implanter 300 comprises a beam deflector 380 to
deflect the ion beam 340 across the surface 112 of the component
114 to distributively implant ions into the component 114. In one
embodiment, the beam deflector 380 comprises an electrostatic
deflector that generates an electric field to deflect the ion beam
340. The electric field has a field component orthogonal to the
propagation direction of the ion beam 340 along which the
electrostatic deflector deflects the ion beam 340. In another
embodiment, the beam deflector 380 comprises a magnetic deflector
that generates a magnetic field to deflect the ion beam. The
magnetic field has a field component orthogonal to the propagation
direction of the ion beam 340, and the magnetic deflector deflects
the ion beam 340 in a direction that is orthogonal to both the
propagation direction of the ion beam 340 and its orthogonal
magnetic field component.
[0045] The ion implanter 300 implants an amount of implanting
material into the structure 111 of the component 114 such that the
ratio of the implanted material to the material of the underlying
structure provides the desired stoichiometry. For example, when
implanting yttrium ions into the surface of an aluminum structure,
it may be desirable to have a molar ratio of aluminum to yttrium of
from about 4:2 to about 6:4, or even about 5:3. This ratio is
optimized to provide YAG when the structure 111 is subsequently
annealed, anodized, or implanted with oxygen ions.
[0046] An annealer 500, as illustrated in FIG. 6, may also be used
to anneal the component 114 to restore any damage to the
crystalline structure of the component 114. For example, the
annealer 500 may "heal" regions of the component 114 that were
damaged during ion implantation by the energetic ions. Typically,
the annealer 400 comprises a heat source 510, such as an incoherent
or coherent electromagnetic radiation source, that is capable of
heating the component 114 to a suitable temperature for annealing.
For example, the annealer 400 may heat the component 114 to a
temperature of at least about 600.degree. C., such as for example,
at least about 900.degree. C. In the embodiment shown in FIG. 6,
the annealer 400 is a rapid thermal annealer 505 comprising a heat
source 510 that includes tungsten halogen lamps 515 to generate
radiation and a reflector 520 to reflect the radiation onto the
component 114. A fluid 525, such as air or water is flowed along
the heat source 510 to regulate the temperature of the heat source
510. In one version, a quartz plate 530 is provided between the
heat source 510 and the component 114 to separate the fluid from
the component 114. The rapid thermal annealer 505 may further
comprise a temperature monitor 540 to monitor the temperature of
the component 114. In one embodiment, the temperature monitor 540
comprises an optical pyrometer 545 that analyzes radiation emitted
by the component 114 to determine a temperature of the component
114.
[0047] Although exemplary embodiments of the present invention are
shown and described, those of ordinary skill in the art may devise
other embodiments which incorporate the present invention, and
which are also within the scope of the present invention. For
example, the metal alloy may comprise other suitable components,
such as other metals without deviating from the scope of the
present invention. Also, the metal alloy may form portions of
chamber components 114 other than those specifically mentioned, as
would be apparent to those of ordinary skill in the art.
Furthermore, the terms below, above, bottom, top, up, down, first
and second and other relative or positional terms are shown with
respect to the exemplary embodiments in the figures and are
interchangeable. Therefore, the appended claims should not be
limited to the descriptions of the preferred versions, materials,
or spatial arrangements described herein to illustrate the
invention.
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